There are currently properties available to purchase for $30K, but they may not be the best for immediate flip or at least a quick flip. If you have $30K to invest, you can choose to look at homes in a bit higher price range and finance the remaining amount either through conventional or private financing. The financing option you choose will depend on the deal and exit strategy.
You can resell a home as quickly as the same day depending on the buyer's financing. If the buyer is using FHA financing, you will have to wait until you have been on title for 90 days until the FHA buyer can purchase the home. There are several alternative options for buyers that want to use FHA financing that I have used to cut down on your holding costs.
Keep in mind there is no one absolute way you have to follow to fix-n-flip or just flip a property. Finding the deal is the main component, then plotting your exit strategy and financing options.
If you need assistance in any area of your fix-n-flip stages, let me know.